Antifouling oligomerization catalyst systems

ABSTRACT

According to one embodiment, a catalyst system that reduces polymeric fouling may comprise at least one titanate compound, at least one aluminum compound, and at least one antifouling agent or a derivative thereof. The antifouling agent may comprise a structure comprising a central aluminum molecule bound to an R1 group, bound to an R2 group, and bound to an R3 group. One or more of the chemical groups R1, R2, and R3 may be antifouling groups comprising the structure —O((CH 2 ) n O) m R4, where n is an integer from 1 to 20, m is an integer from 1 to 100, and R4 is a hydrocarbyl group. The chemical groups R1, R2, or R3 that do not comprise the antifouling group, if any, may be hydrocarbyl groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Non-Provisional patentapplication Ser. No. 15/393,865 filed Dec. 29, 2016, which claimspriority to U.S. Provisional Patent Application No. 62/275,932 filedJan. 7, 2016, which is incorporated into this disclosure by reference inits entirety.

BACKGROUND Field

Embodiments of the present disclosure generally relate to catalystsystems used in ethylene oligomerization and, more specifically, relateto antifouling catalyst systems used in ethylene oligomerization whichreduce undesired polymerization.

Technical Background

1-butene and 1-hexene are important petrochemicals, especially for theproductions of polyethylene. The reaction of ethylene and otheralpha-olefins, especially 1-butene and 1-hexene, forms various grades oflinear low density polyethylene (LLDPE), a useful commercial polymer. Asource of 1-butene is the butene fraction from the effluent of ahydrocarbon cracker, such as a steam cracker or fluidized catalyticcracker. However, the process for recovering 1-butene from such aneffluent requires several difficult process steps that may make theprocess undesirable.

Several commercial processes selectively oligomerize ethylene into alphaolefins such as 1-butene and 1-hexene. A commercially successfuldimerization process is the Alphabutol™ Process, developed by theInstitute Francais du Petrole (IFP), described in A. Forestiere, et al.,“Oligomerization of Monoolefins by Homogenous Catalysts”, Oil & Scienceand Technology—Review de l'Institute Francais du Petrole, pages 663-664(Volume 64, Number 6, November 2009). This process uses a bubble-pointreactor that contains 1-butene as a process fluid to oligomerizeethylene selectively into 1-butene.

There is a known problem with oligomerization systems: polymerformation. Long residence times and poor heat removal from the highlyexothermic reactions lead to the formation of polyethylene-basedresidues. A side effect of chronic fouling is increasingly frequentprocess shutdowns and higher maintenance costs for removing adheredpolymer residues. Polymer residues may build layer upon layer andeventually close off openings and ports in locations with fluid flow.Additionally, a polymer coating along the wall of a reactor may act asan insulator, which may negatively affect heat transfer to the reactorsystem. Polymer can also collect debris that can be catalytically activeor that can poison the reaction process.

An especially troublesome issue is the formation of “hot spots”. A hotspot is an area where external cooling is ineffective and catalystactivity is high. It represents a loss of process control. A hot spotcan be an area of collected polymer that includes catalytically activematerial that fosters side-reactions, including polymerization. If leftunchecked, the hot spot can eventually lead to a process shutdown due tothe loss of cooling capacity, a runaway polymerization reaction, orboth.

SUMMARY

There is a continual need for effective methods to prevent polymericfouling on reactor system walls and tubes while maintaining the desiredoligomerization rate and selectivity to form reaction product.

According to one embodiment, a catalyst system that reduces polymericfouling may comprise at least one titanate compound, at least onealuminum compound, and at least one antifouling agent or a derivativethereof. The antifouling agent may comprise a structure comprising acentral aluminum molecule bound to an R1 group, bound to an R2 group,and bound to an R3 group. One or more of the chemical groups R1, R2, andR3 may be antifouling groups comprising the structure—O((CH₂)_(n)O)_(m)R4, where n is an integer from 1 to 20, m is aninteger from 1 to 100, and R4 is a hydrocarbyl group. The chemicalgroups R1, R2, or R3 that do not comprise the antifouling group, if any,may be hydrocarbyl groups.

According to another embodiment, 1-butene may be produced by a processcomprising contacting ethylene with a catalyst system to oligomerize theethylene to form 1-butene. The catalyst system may comprise at least onetitanate compound, at least one aluminum compound, and at least oneantifouling agent or a derivative thereof. The antifouling agent maycomprise a structure comprising a central aluminum molecule bound to anR1 group, bound to an R2 group, and bound to an R3 group. One or more ofthe chemical groups R1, R2, and R3 may be antifouling groups comprisingthe structure —O((CH₂)_(n)O)_(m)R4, where n is an integer from 1 to 20,m is an integer from 1 to 100, and R4 is a hydrocarbyl group. Thechemical groups R1, R2, or R3 that do not comprise the antifoulinggroup, if any, may be hydrocarbyl groups.

Additional features and advantages of the embodiments described hereinwill be set forth in the detailed description which follows, and in partwill be readily apparent to those skilled in the art from thatdescription or recognized by practicing the embodiments described,including the detailed description which subsequently follows, and theclaims.

DETAILED DESCRIPTION

One or more embodiments of the present disclosure are directed tocatalyst systems which may be utilized in promoting ethyleneoligomerization, such as the dimerization of ethylene to form 1-butene,while reducing reactor fouling caused by undesired polymerization. Thesecatalyst systems are sometimes referred to in this disclosure as“antifouling ethylene oligomerization catalyst systems” or “antifoulingcatalyst systems”. The antifouling catalyst systems described maycomprise at least one titanate compound, at least one aluminum compound,and at least one antifouling agent or dimer thereof. The antifoulingcatalyst systems may further comprise one or more ether compounds. Theantifouling catalyst systems may be used to selectively oligomerizeethylene to produce 1-butene, while reducing undesirable polymerization,sometimes referred to in this disclosure as “fouling”. For example,reactor fouling may occur due to the formation of solidpolyethylene-based residues which may reduce fluid flow and fully blockor at least partially block fluids in a reactor system from flowing at adesired rate. It should be understood that the “antifouling ethyleneoligomerization catalyst systems” or “antifouling catalyst systems”described may not completely eliminate fouling during a reaction.However, these catalyst systems reduce fouling as compared with catalystsystems which do not include an antifouling agent as described in thepresent disclosure. Also, it should be understood that while thecatalyst systems of the present disclosure may be useful in ethyleneoligomerization reactions, such as ethylene dimerization to form1-butene, they may also be useful for the catalysis of other chemicalreaction, and the antifouling catalyst systems described in thisdisclosure should not be considered limited in their use to thedimerization of ethylene to 1-butene.

As described previously in this disclosure, embodiments of the describedantifouling catalyst systems may comprise one or more titanatecompounds. While several titanate compounds may be included in theantifouling catalyst system, in some embodiments a single titanatecompound may be included in the antifouling catalyst system. In one ormore embodiments, the titanate compound may be an alkyl titanate. Analkyl titanate may have the structure Ti(OR)₄ in which R is a branchedor straight chain alkyl group. In one or more embodiments, each alkylgroup may comprise from 2 to 8 carbons, where each R group may be thesame or different. Suitable alkyl titanates may include tetraethyltitanate, tetraisopropyl titanate, tetra-n-butyl titanate (sometimesreferred to as titanium butoxide or tetrabutyl orthotitanate),2-tetraethylhexyl titanate. In one or more embodiments, the titanatecompound of the antifouling catalyst system consists of tetra-n-butyltitanate.

As also described previously in this disclosure, embodiments of thedescribed antifouling catalyst systems may comprise one or more aluminumcompounds. While several aluminum compounds may be included in theantifouling catalyst system, in some embodiments a single aluminumcompound may be included. In one or more embodiments, one or morealuminum alkyl compounds may be included in the antifouling catalystsystem. Aluminum alkyl compounds may have a structure of AlR′₃ orAlR′₂H, where R′ is a straight chain or branched alkane comprising from1 to 20 carbons, or an aluminoxane structure (that is, a partialhydrolysate of trialkylaluminum compounds). For example, and not by wayof limitation, suitable aluminum alkyl compounds may includetriethylaluminum, tripropylaluminum, tri-iso-butylaluminum, andtrihexylaluminum. In one or more embodiments, the aluminum compound ofthe antifouling catalyst system consists of triethylaluminum.

The antifouling catalyst systems may comprise one or more antifoulingagents or derivatives thereof. As used herein, a derivative refers to aderivative structure of an antifouling agent, such as a dimer, trimer,oligomer, polymer, isomer, hydrolysate of an antifouling agent describedin this disclosure. In one or more embodiments, an antifouling agent maycomprise a central aluminum molecule bonded to all three of a firstchemical group R1, a second chemical group R2, and a third chemicalgroup R3. Chemical Structure #1 depicts a generalized chemical structureof an antifouling agent.

Chemical Structure #1—Generalized Antifouling Agent

In one or more embodiments, one or more of R1, R2, and R3 areantifouling groups comprising the structure —O((CH₂)_(n)O)_(m)R4, wheren is an integer from 1 to 20 (for example, 1 to 15, 1 to 10, 1 to 5, 1to 4, 1 to 3, 1 to 2, 2 to 20, 3 to 20, 4 to 20, 5 to 20, 10 to 20, or15 to 20), m is an integer from 1 to 100 (for example, 1 to 10, 1 to 20,1 to 30, 1 to 40, 1 to 50, 1 to 75, 5 to 100, 10 to 100, 25 to 100, 50to 100, or 75 to 100), and R4 is a hydrocarbyl group. The structure ofthe antifouling group, —O((CH₂)_(n)O)_(m)R4, is depicted in ChemicalStructure #2. The central aluminum atom is bonded to a terminal oxygenof the antifouling group opposite of the R4 hydrocarbyl group. As usedthroughout this disclosure, a hydrocarbyl group refers to a chemicalgroup that consists of hydrogen and carbon atoms. For example, ahydrocarbyl group may be branched or unbranched, and may comprise one ormore alkane moieties, one or more alkene moieties, one or more alkynemoieties, or combinations thereof. Hydrocarbyl groups may include cyclicor aromatic moieties. In one or more embodiments, R4 may be ahydrocarbyl group having from 1 to 100 carbon atoms, such as from 5 to50 carbon atoms, or from 12 to 28 carbon atoms.

Chemical Structure #2—Antifouling Group

As previously described in this disclosure, one, two, or all three ofR1, R2, and R3 may comprise the antifouling groups comprising thestructure of Chemical Structure #2. In embodiments described in thisdisclosure, the chemical groups R1, R2, or R3 that do not comprise theantifouling group, if any, are hydrocarbyl groups. For example, R1 maybe an antifouling group with the structure depicted in ChemicalStructure #2 and R2 and R3 may be hydrocarbyl groups. In anotherembodiment, R1 and R2 may be antifouling groups with the structuredepicted in Chemical Structure #2, and R3 may be a hydrocarbyl group. Inanother embodiment, R1, R2, and R3 may be antifouling groups with thestructure depicted in Chemical Structure #2. When at least two of R1,R2, and R3 are hydrocarbyl groups, they may be identical to one anotheror may be different hydrocarbyl groups. Also, when two or more of R1,R2, or R3 are antifouling groups, the antifouling groups may beidentical or chemically different. However, they will each have thegeneric structure depicted in Chemical Structure #2. R1, R2 and R3 thatare hydrocarbyl groups may each have from 1 to 100 carbon atoms, suchas, for example, from 1 to 50 carbon atoms. For example, if R1, R2, orR3 are hydrocarbyl groups, they may be straight chained alkanes such asmethyl, ethyl, propyl, or butyl groups.

By way of example, if R1 is an antifouling group, and R2 and R3 arehydrocarbyl groups, the generalized structure of the antifouling agentcan be represented by Chemical Structure #3.

Chemical Structure #3—Example of Generalized Antifouling Agent

In one or more embodiments, the antifouling agent may comprise an R1group that is an ethyl group, an R2 group that is an ethyl group, and anR3 that is an antifouling group having the structure—O((CH₂)_(n)O)_(m)R4, where n=2, m=4, and R4 is a dodeyl group. Such anantifouling agent can be written as (CH₃CH₂)₂AlO(CH₂CH₂O)₄(CH₂)₁₁CH₃,and has the chemical structure depicted in Chemical Structure #4, where“Et” represents an ethyl group.

Chemical Structure #4—Example of Antifouling Agent

In one or more embodiments, the antifouling agent may be present as adimerized form, referred to herein as an example of a derivative of anantifouling agent. A prepared antifouling agent may be present in bothdimerized and non-dimerized (that is, non-bonded) form. For example, ina dimerized state, the antifouling agent may comprise a structure asshown in Chemical Structure #5. Chemical Structure #5 shows thedimerized embodiment of the antifouling agent structure depicted inChemical Structure #3. In a dimerized embodiment, a bond may formbetween a central aluminum atom of an antifouling agent molecule and anoxygen atom of a neighboring antifouling agent molecule. It should beunderstood that while in Chemical Structures #5 the central aluminumatoms are bonded to the oxygen atom in the neighboring antifouling agentthat is most near to its central aluminum atom, in other embodiments,this may not be the case, and the a central aluminum atom may bond withan oxygen atom of a neighboring antifouling agent which is not most nearto its central aluminum atom.

Chemical Structure #5—Example of Dimerized Antifouling Agent

In one or more embodiments, the antifouling agent may be present indifferent isomer states, one such example depicted in Chemical Structure#6. An isomer is an example of a derivative structure of an antifoulingagent. For example, and as depicted in Chemical Structure #6, thecentral aluminum atom of an antifouling agent may be bonded to twooxygens atoms of a single antifouling group. It should be understoodthat while Chemical Structure #6 depicts an isomer where the two oxygenatoms most near to the central aluminum atom are bonded with the centralaluminum atom, in other embodiments other isomers may form, such as anisomer formed when the central aluminum atom forms a bond with an oxygenatom which is not as close as another oxygen atom to the centralaluminum atom in the antifouling agent molecule. For example, whileChemical Structure #6 shows a ring structure with 2 oxygen atoms and ncarbon atoms, larger ring structures may form in other isomers, such asrings having three or more oxygen atoms. It should be understood thatisomers of the antifouling agents described, such as that shown inChemical Structure #6, are considered antifouling agents and fit intothe base structure depicted in Chemical Structure #1. For instance, theexistence of two oxygen atoms bonded to the central aluminum, where bothoxygen atoms are part of an antifouling group, is considered to conformto the base structure depicted in Chemical Structure #1.

Chemical Structure #6—Example of Isomer of Antifouling Agent

In one or more embodiments, the antifouling catalyst systems maycomprise more than one molecular species of antifouling agent. Forexample, the antifouling catalyst system may comprise antifouling agentswith a varying number of antifouling groups. For example, someantifouling agent molecules may comprise none, one, two or threeantifouling groups, while others comprise a different number ofantifouling groups. The mixture of these antifouling agent species mayform a bulk antifouling agent which can be characterized by its bulkmolar ratio of hydrocarbyl groups to antifouling groups which areattached to the central aluminum atoms, respectively. For example, ifhalf of the antifouling agent has one antifouling group and twohydrocarbyl groups, and, the other half of the antifouling agent has twoantifouling groups and one hydrocarbyl group, then the bulk molar ratioof hydrocarbyl groups to antifouling groups would be 1:1 because thereis a bulk equal amount of hydrocarbyl groups to antifouling groups. Inone or more embodiments, the bulk molar ratio of hydrocarbyl groups toantifouling groups may be from be from 1:1 to 20:1. Non-limitingexamples of bulk molar ratios of hydrocarbyl groups to antifoulinggroups include from 1:1 to 2:1, from 1:1 to 3:1, from 1:1 to 4:1, from1:1 to 5:1, from 1:1 to 10:1, from 1:1 to 15:1, from 2:1 to 20:1, from3:1 to 20:1, from 4:1 to 20:1, from 5:1 to 20:1, from 10:1 to 20:1, orfrom 15:1 to 20:1. According to one or more embodiments, the bulk molarratio of hydrocarbyl groups to antifouling groups is from 1.5 to 2.5,from 1.8 to 2.2, or 2.

In one or more embodiments, the antifouling catalyst system may compriseone or more ether compounds. The one or more ether compounds may includecyclic ethers such as, but not limited to, tetrahydrofuran (THF), adioxane, a Tetrahydropyran (THP), or combinations thereof.

The antifouling catalyst systems may comprise at least one or moretitanate compounds, one or more aluminum compounds, and one or moreantifouling agents. In one or more embodiments, the molar ratio of totaltitanate compound to total aluminum compound may be from 1:10 to 1:1.5(such as, for example, from 1:10 to 1:2, from 1:10 to 1:3, from 1:10 to1:4, from 1:10 to 1:5, from 1:10 to 1:6, from 1:10 to 1:7, from 1:10 to1:8, from 1:10 to 1:9, from 1:9 to 1:1.5, from 1:8 to 1:1.5, from 1:7 to1:1.5, from 1:6 to 1:1.5, from 1:5 to 1:1.5, from 1:4 to 1:1.5, from 1:3to 1:1.5, or from 1:2 to 1.5).

In one or more embodiments, the molar ratio of total titanate compoundsto total antifouling agent may be from 1:5 to 1:0.01 (such as, forexample, from 1:5 to 1:0.05, from 1:5 to 1:0.1, from 1:5 to 1:0.3, from1:5 to 1:0.5, from 1:5 to 1:0.7, from 1:5 to 1:1, from 1:5 to 1:2, from1:5 to 1:3, from 1:5 to 1:4, from 1:4 to 1:0.01, from 1:3 to 1:0.01,from 1:2 to 1:0.01, from 1:1 to 1:0.01, from 1:0.7 to 1:0.01, or from1:0.3 to 1:0.01).

In one or more embodiments, the molar ratio of total titanate compoundsto total ether compounds may be from 1:20 to 1:0 (such as, for example,from 1:15 to 1:0, from 1:10 to 1:0, from 1:5 to 1:0, from 1:1 to 1:0,from 1:0.5 to 1:0, from 1:0.3 to 1:0, from 1:0.1 to 1:0, from 1:20 to1:0.1, from 1:20 to 1:0.5, from 1:20 to 1:1, from 1:20 to 1:5, from 1:20to 1:10).

It should be understood that the molar ratios of components of theantifouling catalyst systems described previously are representative ofthe total amount of each component of the antifouling catalyst systemrelative to the total amount of titanate compound, where the “total”amount refers to the molar amount of all species of the antifoulingcatalyst system which may be considered as a particular component type(that is, titanate compound, aluminum compound, ether compound, orantifouling agent). The total amount of a component may include two ormore chemical species which are titanate compounds, aluminum compounds,ether compounds, or antifouling agents, respectively. It should also beunderstood that, as used in this disclosure, the total amount ofaluminum compound does not include molecules that are considered asantifouling agents. Therefore, any species that is considered anantifouling agent as described in this disclosure does not contributetowards the total amount of aluminum compound even though theantifouling agent includes an aluminum central atom and may otherwise beconsidered as an aluminum-containing compound.

In one or more embodiments, the antifouling agent does not dealkylate,or is resistant to dealkylation as compared with other catalyst systems.Ethane releasing reactions may be undesirable, as they can contaminate afeed stream. In one or more embodiments, the antifouling agent does notdeactivate the catalytic centers of one or more of the titanate compoundor the aluminum compound.

According to another embodiment of the present disclosure, 1-butene maybe produced. According to the method for 1-butene production, ethylenemay be contacted with the antifouling catalyst system describedpreviously to oligomerize the ethylene to form 1-butene. In one or moreembodiments, the ethylene and antifouling catalyst system are suppliedto a reactor and mixed. The reaction may be performed as a batchreaction or as a continuous process reaction, such as a continuous stirtank reactor process. According to embodiments, the pressure of thereactor may be from 5 bar to 100 bar, the reactor temperature may befrom 30 degrees Celsius (° C.) to 180° C. However process conditionsoutside of these ranges are contemplated, especially in view of thespecific design of the reactor system and concentrations of thereactants and catalysts.

Examples

The various embodiments of antifouling catalyst systems will be furtherclarified by the following examples. The examples are illustrative innature, and should not be understood to limit the subject matter of thepresent disclosure.

To form an antifouling agent having the chemical structure(CH₃CH₂)₂AlO(CH₂CH₂O)₄C₁₂H₂₅ (shown as Chemical Structure #4), 10milliliters (mL) of triethyl aluminum (1 molar (M) in hexane) wasreacted with 10 mL of polyethylene glycol dodecyl ether (1 M in hexane).Specifically, polyethylene glycol dodecyl ether was first dried withanhydrous grade sodium sulfate to remove any residual moisture. Thedried polyethylene dodecyl ether was then added drop-wise to thetriethyl aluminum in a 30 mL flask. The reaction mixture wassubsequently stirred for 15 minutes. The reaction was carried out in aninert atmosphere inside a glove box. Light color change and release ofethane gas were observed during the reaction. Other antifouling agentswere produced though similar techniques which incorporated reactantssuitable to achieve antifouling agents having varying values of n, m,and R4 as described in this disclosure with reference to antifoulinggroups.

To evaluate the anti-fouling effects of the antifouling catalyst systemsdescribed, ethylene oligomerization reactions were carried out andevaluated. Multiple sample anti-fouling catalyst systems wereformulated. Detailed structure of the antifouling agents used, as wellas ratios of are listed in Table 1, For the experiments, catalystmixtures were used that contained titanium tetrabutoxide (denoted as“Ti” in Table 1), THF, triethyl aluminum (denoted as “TEAL” in Table 1),and antifouling agents (denoted as “AFA” in Table 1). The antifoulingagents utilized are described previously in this disclosure and aredepicted in Chemical Structure #3 (where for the experiments, R2 and R3are ethyl groups, and n, m, and R4 are specified in Table 1). Inaddition to the catalyst mixtures containing antifouling agent,comparative examples which did not contain antifouling agent were testedand compared with the catalyst systems which included antifoulingagents.

The components of the sample catalyst systems were prepared andtransferred into metal charging cylinders in a glove box. The THF waspremixed with the titanium tetrabutoxide (in samples where TI-IF wasincluded) and transferred to a charging cylinder, and the antifoulingagent was premixed with the triethyl aluminum in heptane (1 M) utilizedas a solvent. The oligomerization reactions were conducted in anautoclave batch reactor unit (1000 mL, volume). In a typical reactionrun, the reactor vessel was vacuum purged with ultrapure nitrogen toremove oxygen and moisture. Then, the batch reactor was filled withanhydrous hexane and kept at 50° C. The anti-fouling agent and triethylaluminum solution in heptane (1M) was then introduced into the reactionvessel. Then, the pre-mixed solution containing titanium tetrabutoxideand THF was introduced into the reactor. The catalyst solution had aconcentration of titanium tetrabutoxide of 1 micromolar. Followingintroduction of the components of the catalyst system, the reactor waspressurized to 2.3 mega-Pascals (MPa) with ethylene and the temperatureof the reactor was set to 53° C. with a stirring rate of 300 rpm. Thedimerization reaction was terminated by injecting 2 mL, of ethanol after30 minutes. The reactor was subsequently depressurized. The remainingsolid polymer was filtered, dried overnight in an oven at 110° C. andweighed.

Table 1 shows the dimerization activity and weight of polymer depositfor reactions which utilized each of the sample catalyst systems. As isevident by the reaction data of Table 1, the addition of the antifoulingadditive greatly reduced polymer formation.

TABLE 1 Activity (grams of ethylene per hour Molar Ratio per millimolesPolymer of Ti:THF:TEAL:AFA n m R4 of titanium Produced (mg) Comparative1:4:7.5:0 N/A N/A N/A 221 200 Example 1 Example 1 1:4:7:0.4 2  4C₁₂H₂₅-n 291  35 Example 2 1:4:7.5:3 2 10 C₁₈H₃₇-n 224  21 Example 31:4:7.5:3 2 20 C₁₈H₃₇-n 228  78 Comparative 1:6:7.5:0 N/A N/A N/A 190187 Example 2 Example 4 1:6:7.5:0.6 2  4 C₁₂H₂₅-n 254 N/A Comparative1:6:7.5:0 N/A N/A N/A 278  91 Example 3 Example 5 1:6:7.5:0.6 2  2C₁₈H₃₇-n 276   4 Example 6 1:6:7.5:0.6 2  4 C₁₂H₂₅-n 289   6 Example 71:6:7.5:1 2  4 C₁₂H₂₅-n 263   4

What is claimed is:
 1. A catalyst system that reduces polymeric fouling,the catalyst system comprising: at least one titanate compound; at leastone aluminum compound; and at least one antifouling agent or a dimer,trimer, oligomer, polymer, or isomer, where the antifouling agentcomprises the structure:

where R1, R2, and R3 are antifouling groups comprising the structure—O((CH₂)_(n)O)_(m)R4, where: n is an integer from 1 to 20; m is aninteger from 1 to 100; and R4 is a hydrocarbyl group.
 2. The catalystsystem of claim 1, where n is from 1 to
 5. 3. The catalyst system ofclaim 1, where m is from 1 to
 20. 4. The catalyst system of claim 1,where R4 has from 1 to 100 carbon atoms.
 5. The catalyst system of claim1, further comprising an ether compound.
 6. The catalyst system of claim5, where the ether compound is tetrahydrofuran, a dioxane, ortetrahydropyran.
 7. The catalyst system of claim 1, where at least oneof the titanate compounds is an alkyl titanate.
 8. The catalyst systemof claim 7, where the alkyl titanate has the structure Ti(OR)₄, where Ris a branched or straight chain alkyl radical comprising from 2 to 8carbon atoms.
 9. The catalyst system of claim 7, where the alkyltitanate is chosen from tetraethyl titanate, tetraisopropyl titanate,tetra-n-butyl titanate, or 2-tetraethylhexyl titanate.
 10. The catalystsystem of claim 1, where at least one of the aluminum compounds has thestructure AlR′₃ or AlR′₂H, where R′ is a branched or straight chainalkyl radical comprising from 2 to 8 carbon atoms.
 11. The catalystsystem of claim 1, where at least one of the aluminum compounds ischosen from triethylaluminum, tripropylaluminum, tri-iso-butylaluminum,trihexylaluminum, or an aluminoxane.
 12. The catalyst system of claim 1,where a molar ratio of total titanate compound to total aluminumcompound is from 1:10 to 1:1.5.
 13. The catalyst system of claim 1,where a molar ratio of total titanate compound to total antifoulingagent is from 1:5 to 1:0.01.
 14. The catalyst system of claim 1, where amolar ratio of total titanate compound to total ether compound is from1:10 to 1:0.
 15. The catalyst system of claim 1, where the catalystsystem comprises one or more of the at least one antifouling agent, thedimer of the antifouling agent, and the isomer of the antifouling agent.16. The catalyst system of claim 1, where the catalyst system comprisesone or more of the at least one antifouling agent and the dimer of theantifouling agent, wherein the dimer of the antifouling agent has thestructure:

where R2, and R3 are antifouling groups comprising the structure—O((CH₂)_(n)O)_(m)R4, where: n is an integer from 1 to 20; m is aninteger from 1 to 100; and R4 is a hydrocarbyl group.
 17. A catalystsystem that reduces polymeric fouling, the catalyst system comprising:at least one titanate compound; at least one aluminum compound; at leastone ether compound; and at least one antifouling agent or a dimer,trimer, oligomer, polymer, or isomer, where the antifouling agentcomprises the structure:

where R1, R2, and R3 are antifouling groups comprising the structure-O((CH₂)_(n)O)_(m)R4, where: n is an integer from 1 to 20; m is aninteger from 1 to 100; and R4 is a hydrocarbyl group. a molar ratio oftotal titanate compound to total ether compound is from 1:10 to 1:0. 18.The catalyst system of claim 17, where at least one of the aluminumcompounds has the structure AlR′₃ or AlR′₂H, where R′ is a branched orstraight chain alkyl radical comprising from 2 to 8 carbon atoms. 19.The catalyst system of claim 17, where a molar ratio of total titanatecompound to total aluminum compound is from 1:10 to 1:1.5.
 20. Thecatalyst system of claim 17, where a molar ratio of total titanatecompound to total antifouling agent is from 1:5 to 1:0.01.